IEEE (Institute of Electrical and Electronics Engineers) Standard 802.1Q entitled “Virtual Bridged Local Area Networks” publication date of Mar. 8, 1999, defines an industry standard for virtual bridged local area networks (VLANs). The 802.1Q standard, among other things, defines a convention for adding a tag header to a Layer 2 data packet, i.e. a “frame”, in the creation of an 802.1 Q-compliant packet. The tag header may include, among other things, a VLAN Identifier and a priority value assigned to the packet. The VLAN Identifier typically determines what LAN devices are authorized to receive the packet, and the priority value typically determines how fast the packet will be received by the authorized LAN devices relative to other packets.
As an 802.1Q-compliant packet passes through each bridge in a bridged LAN, the priority value in the inbound packet may be “regenerated” by the bridge to determine a corresponding priority value for the outbound packet. According to the standard, the outbound priority value may be independently determined on each bridge as a function of the port on which the bridge receives the packet and the inbound priority value. There is no provision in the standard, however, to take into account values from fields in the packet that are not dedicated to defining quality of service (QoS) when assigning the outbound priority value.
Therefore, it is desirable to take into account values from fields in the packet that are not dedicated to defining QoS when assigning the outbound priority value. It may also be desirable to assign distinct internal and outbound priority values to the packet, the former for application in prioritizing the packet on the current bridge and the latter for application to the packet as transmitted from the current bridge.